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CN119465448B - Preparation method of hollow cross-section polyacrylonitrile dry-jet wet-spun carbon fiber - Google Patents

Preparation method of hollow cross-section polyacrylonitrile dry-jet wet-spun carbon fiber

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Publication number
CN119465448B
CN119465448B CN202411602136.XA CN202411602136A CN119465448B CN 119465448 B CN119465448 B CN 119465448B CN 202411602136 A CN202411602136 A CN 202411602136A CN 119465448 B CN119465448 B CN 119465448B
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China
Prior art keywords
plate body
temperature
holes
needle
fiber
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Application number
CN202411602136.XA
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Chinese (zh)
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CN119465448A (en
Inventor
张国良
陈秋飞
刘栋
张金元
王刚
刘琦
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Zhongfu Shenying Carbon Fiber Co Ltd
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Zhongfu Shenying Carbon Fiber Co Ltd
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Priority to CN202411602136.XA priority Critical patent/CN119465448B/en
Publication of CN119465448A publication Critical patent/CN119465448A/en
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Classifications

    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F9/00—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments
    • D01F9/08—Artificial filaments or the like of other substances; Manufacture thereof; Apparatus specially adapted for the manufacture of carbon filaments of inorganic material
    • D01F9/12—Carbon filaments; Apparatus specially adapted for the manufacture thereof
    • D01F9/14—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments
    • D01F9/20—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products
    • D01F9/21—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F9/22—Carbon filaments; Apparatus specially adapted for the manufacture thereof by decomposition of organic filaments from polyaddition, polycondensation or polymerisation products from macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from polyacrylonitriles
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/06—Wet spinning methods
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/24—Formation of filaments, threads, or the like with a hollow structure; Spinnerette packs therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/28—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D01F6/38—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from copolymers obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising unsaturated nitriles as the major constituent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
    • Y02P70/62—Manufacturing or production processes characterised by the final manufactured product related technologies for production or treatment of textile or flexible materials or products thereof, including footwear

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Inorganic Fibers (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)

Abstract

The invention discloses a preparation method of hollow section polyacrylonitrile dry-jet wet-spinning carbon fiber. The method comprises the steps of extruding spinning solution through a spinneret plate with an annular cavity, entering a coagulating bath, carrying out multistage desalting and water washing, hot water drafting, oiling, drying and densification, winding and filament collecting after steam drafting to obtain a hollow section precursor, and carrying out preoxidation, low-temperature furnace and high-temperature furnace carbonization on the hollow section precursor to obtain the dry-jet wet-spun carbon fiber with a hollow section. The preparation method is simple, the effective control of the hollow-section polyacrylonitrile carbon fiber structure is realized by controlling the structure of the spinneret plate with the annular cavity and the subsequent process conditions, and the prepared hollow-section carbon fiber has the advantages of high specific surface area, low sheath-core ratio, low cost and the like, and has wide application prospects in the fields of wave-absorbing materials, electromagnetic shielding materials, resin-based composite materials, carbon/carbon composite materials and the like.

Description

Preparation method of hollow section polyacrylonitrile dry-jet wet-spinning carbon fiber
Technical Field
The invention relates to a preparation method of hollow section polyacrylonitrile dry-jet wet-spinning carbon fiber, belonging to the technical field of carbon fiber preparation.
Background
Hollow fiber is fiber with hollow cavity in axial direction, and has special cross section, so that the surface area of hollow fiber is raised greatly compared with circular fiber, and the compounding performance with matrix is expected to be improved greatly; the hollow fiber has high heat insulating performance, high surface area and high fiber bulkiness, and has high water, gas, blood and other medium adsorbing capacity, high matrix material combining capacity, high fiber rigidity, high fiber hardness, high fiber bending resistance and high fiber wear resistance. If the hollow element is filled in the interior, it is expected to prepare hollow fibers having some special functions. At present, the hollow section of the fiber is mainly prepared by methods of melt spinning, electrostatic spinning, wet spinning and the like, and the hollow fiber mainly comprises polyester fiber, glass fiber, carbon fiber, nanofiber and the like, and chemical materials such as polypropylene (PP), polyester, polyamide, polyacrylonitrile, polystyrene, polyethylene, nylon, cellulose acetate, various nylon, terylene, acrylic fiber, polypropylene fiber and the like can be prepared into the hollow fiber by a proper spinning process.
The dry-jet wet spinning technology can effectively improve the mechanical property and spinning speed of polyacrylonitrile fibers, is a technology capable of being achieved through engineering, but is extremely complicated in dry-jet wet spinning process, under the action of surface tension, the forming process of spinning stock solution with viscoelastic characteristics after passing through special hollow spinning holes is far more complicated than the forming process after passing through round spinning holes, extrusion expansion of spinning stock solution after passing through the special hollow spinning holes occurs, but because of the structural difference of the hollow spinning holes, the shearing action of the stock solution is uneven, fine flow breakage is easily caused, the design of the inner diameter and the outer diameter of a spinneret plate is critical, however, if the difference of the inner diameter and the outer diameter is too small, under the condition of larger N 2 pressure, the solution is easy to break after extrusion, the hollow fibers are difficult to bear stronger driving force in the coagulation bath process, the compactness is poor, and if the difference of the inner diameter and the outer diameter are too large, the solution is easy to be adhered into round solid filaments through an air layer after extrusion, so that the deviation of the hollow fibers is too large. The hollow carbon fiber thus prepared is required to have a suitable inside-outside diameter ratio, E i defined as:
The relative deviation S is determined by the internal-external diameter ratio of the fiber Ei and inner and outer diameter of spinneret plate the ratio of the absolute value of the difference E to the inner and outer diameter E of the spinneret plate is shown as follows:
Wherein D is the inscribed circle diameter of the hollow-section carbon fiber, A 1 is the cross-sectional shadow area of the hollow-section carbon fiber, D is the circumscribed circle diameter of the hollow-section carbon fiber, and A 0 is the circumscribed circle area of the fiber. The hollow section fiber has special surface morphology, so that oxygen can more easily permeate into the fiber in the pre-oxidation process, on one hand, the radial non-uniformity of the fiber is relieved, the uniformity of the pre-oxidized fiber filaments is improved, the sheath-core rate of the carbon fiber is reduced, on the other hand, the reaction rate is improved, the wire feeding process is reduced, the reaction time is reduced, the running temperature of a reaction furnace is reduced, the rapid preparation of the carbon fiber is realized, and the production cost is reduced.
Disclosure of Invention
The invention aims to provide a preparation method of hollow section polyacrylonitrile dry-jet wet-spinning carbon fiber. The method comprises the steps of firstly spraying spinning solution through a spinneret plate with an annular containing cavity, then entering a coagulating bath to form nascent fibers with hollow sections, carrying out multistage desalination and water washing, water drawing, oiling, drying and steam drawing on the fibers, and winding and filament collecting to obtain filaments with hollow sections, and carrying out preoxidation and carbonization on the filaments to obtain carbon fibers with hollow sections.
The technical scheme for realizing the purpose of the invention is as follows:
The preparation method of the hollow cross-section polyacrylonitrile dry-jet wet-spinning carbon fiber comprises the following steps:
(1) Taking 95-99wt.% of acrylonitrile as a first monomer, and taking 1-5wt.% of acrylic acid, methyl acrylate, methyl methacrylate or isobutyl methacrylate as a second monomer, and performing solution polymerization in dimethyl sulfoxide to obtain a spinning solution, wherein the temperature of the spinning solution is controlled to be 40-70 ℃ and the solid content is controlled to be 10-25%;
(2) Extruding the spinning solution through a spinneret plate with an annular cavity at the extrusion speed of 10-20 m/min after removing single bubble, separating the gel fine strips by solidification phase in a dimethyl sulfoxide coagulating bath through an air layer, and simultaneously carrying out drafting to obtain nascent fibers with a hollow section, wherein the coagulating bath concentration is 30-50wt% and the coagulating bath temperature is 5-20 ℃, the spinneret plate with the annular cavity comprises a first plate body 1 and a second plate body 2, a plurality of through holes 4 and a plurality of needle-containing cylinders 8 are arranged on the first plate body 1, an annular groove 3 is arranged at the top of the spinneret plate body, an annular groove 5 is arranged at the bottom of the spinneret plate body, a plurality of micropore-containing through holes 9 are arranged on the second plate body 2, the needle-containing cylinders 8 on the first plate body and the second plate body 2 are jointed to form a pulp inlet channel 6, the needle-containing cylinders 8 on the first plate body and the second plate body are in one-to-one correspondence to form an annular cavity 7, the pulp inlet channel 6 is connected with the pulp inlet channel 6, the annular cavity 7 is connected with the needle inlet channel 6, the annular groove 3 is provided with the annular groove 3, the annular groove 3 is provided with the annular groove 5, the diameter of the needle-containing cylinders 9 is arranged at the top of the spinneret plate body and the tip of the first plate body and has the diameter of the needle cylinder 1-5 and the needle-containing cylinders is 0.1-1-5 mm and the diameter is equal to the diameter of the needle-1.0 mm and 0.1-5 mm to the diameter of the capillary body is provided with the needle-1.1 and is provided with the diameter of the needle-1 hole diameter of the needle cylinder and is 0;
(3) The primary fiber is subjected to multistage desalination water washing to remove solvent, water washing, hot desalted water washing and drafting;
(4) Oiling the fiber after hot water drafting, and drying and densification by a hot roller;
(5) The fiber after drying and densification enters into steam drafting, and is coiled and formed after the steam drafting, so as to obtain a hollow section precursor;
(6) The hollow section precursor enters a pre-oxidation furnace for pre-oxidation through a filament withdrawing frame to obtain pre-oxidized filaments;
(7) The pre-oxidized fiber is carbonized through a low-temperature furnace and a high-temperature furnace in sequence to prepare the carbon fiber with the hollow section, wherein the temperature of the low-temperature furnace is 580-650 ℃, the draft multiple of the low-temperature furnace is 1.0-1.1 times, the temperature of the high-temperature furnace is 1450-1600 ℃, and the draft multiple of the high-temperature furnace is 0.95-1.05 times.
In the step (2), the method for removing the single fiber comprises the steps of removing the single fiber from the spinning solution under the pressure of-76 Kpa in a single removing kettle, performing primary filtration treatment of 3 mu m, performing defoaming treatment in a defoaming kettle with the pressure of-97 KPa, and then delivering to secondary filtration of 1 mu m for treatment.
Further, in the step (2), the height of the air layer is 1-5 mm, and the air draft multiple is 1-2 times. Preferably, the coagulation bath concentration is 45wt% and the coagulation bath temperature is 5 ℃.
Further, in the step (2), the number of holes of the through holes 4 is 1-2K, the number of holes of the needle-containing cylinder 8 and the micropore-containing through holes 9 is 1-5K, and the needle length of the needle-containing cylinder 8 and the micropore length of the micropore-containing through holes 9 are 0.3-1.0 mm; the length of the cylinder in the needle-containing cylinder 8 is 10-15 mm, the diameter of the cylinder is 3-5 mm, the length of the through hole in the micropore-containing through hole 9 is 5-8 mm, the diameter of the through hole is 4-6 mm, and the hole spacing is 1-3 mm.
Further, in the step (2), the spinneret plate with the annular cavity is made of hastelloy C276, 316lL alloy, 1Cr18Ni9Ti austenitic stainless steel, AISI316 or AISI630.
Further, in the step (3), the washing tank is 3-7 stages, the washing temperature is 20-36 ℃, the draft multiple is 1-1.5 times, the hot desalted water washing and the draft are 1-3 stages, the temperature is 60-80 ℃, and the draft multiple is 1-2.0 times.
Further, in the step (4), the temperature of the hot roller is 3-7 grades, the temperature interval is 100-185 ℃, and the pressure of the hot roller is 0.30-1.10 MPa.
Further, in the step (5), the steam pressure is 0.30-0.80 MPa, the steam draft multiple is 3.0-5.0 times, and the winding speed is 350-500 m/min.
Further, in the step (6), the pre-oxidation temperature is 200 ℃ to 300 ℃ and the pre-oxidation draft is 0.9 to 1.05 times. Preferably, the pre-oxidation temperature is 220 ℃ to 240 ℃.
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the invention, the spinneret plate with the annular cavity is designed, and is successfully applied to a dry-jet wet spinning method for preparing the polyacrylonitrile carbon fiber with the hollow section;
(2) The invention realizes the effective control of the hollow section polyacrylonitrile carbon fiber structure by controlling the sizes of the needle-containing cylinder, the micropore-containing through hole and the length-diameter ratio of the spinneret orifice in the spinneret plate with the annular cavity and simultaneously matching with the proper coagulation bath conditions;
(3) The hollow section carbon fiber prepared by the method has the advantages of high specific surface area, high compactness, low sheath-core ratio, high filling ratio, high wave absorbing performance, high tensile strength, low cost and the like, can be loaded with other mediums to improve the comprehensive performance of the composite material when being used as a two-dimensional reinforcing material, and is suitable for the fields of preparing wave absorbing materials, electromagnetic shielding materials, radar wave absorbing materials, resin-based composite materials, carbon/carbon composite materials, functional materials, structural materials, stealth weapons and the like.
Drawings
FIG. 1 is a schematic outline view of the overall structure of a spinneret plate;
FIG. 2 is a partial enlarged profile at I in FIG. 1;
FIG. 3 is a schematic view of the structure of the first plate body;
FIG. 4 is a schematic three-view of the structure of the second plate;
In the figure, the reference numerals are 1 a first plate body, 2a second plate body, 3 annular grooves, 4 through holes, 5 annular grooves, 6 slurry inlet channels, 7 annular cavities, 8 needle-containing cylinders and 9 micropore through holes.
Detailed Description
The technical solutions of the present invention will be clearly and completely described below with reference to the examples and the accompanying drawings, and it is apparent that the described examples are only some but not all examples of the present invention, and that all other examples obtained by those skilled in the art without making creative efforts based on the examples of the present invention are within the scope of protection of the present invention.
As shown in figures 1-4, the spinneret plate comprises a first plate body 1 and a second plate body 2, wherein a plurality of through holes 4 and a plurality of needle-containing cylinders 8 are formed in the first plate body 1, an annular groove 3 is formed in the top of the annular groove, an annular groove 5 is formed in the bottom of the annular groove, a plurality of micropore-containing through holes 9 are formed in the second plate body 2, the first plate body 1 and the second plate body 2 are attached to each other to form a pulp inlet channel 6, annular cavities 7 are formed in the needle-containing cylinders 8 in the first plate body and the micropore-containing through holes 9 in the second plate body in one-to-one correspondence, the through holes 4 are connected with the pulp inlet channels 6, the pulp inlet channels 6 are connected with the annular cavities 7, rubber rings are arranged in the annular groove 3 and the annular groove 5, and the top of the second plate body 2 is propped against the bottom of the first plate body 1. The top of the first plate body 1 is propped against the stock solution feeding pipeline.
Specifically, the first plate body 1 has a circular shape. The through holes 4 are uniformly distributed along the circumferential direction of the first plate body 1, and the number of the through holes 4 is 1-2K. The needle-containing cylinder 8 is located on the inner periphery of the through hole 4 and evenly distributed along the circle center of the first plate body 1, the number of holes of the needle-containing cylinder 8 is 1-5K, the length of the cylinder is 10-15 mm, the diameter of the cylinder is 3-5 mm, the length of the needle is 0.3-1.0 mm, and the diameter of the needle is 0.3-0.8 mm.
Specifically, the second plate body 2 has a circular shape. The number of the holes of the through holes 9 containing the micropores is 1-5K, the length is 5-8 mm, the diameter is 4-6 mm, the hole spacing is 1-3 mm, the lengths of the micropores in the through holes 9 containing the micropores are 0.3-1.0 mm as the lengths of the needles of the cylinders 8 containing the needles, the pore diameters of the micropores are 0.5-1.5 mm, and the length-diameter ratio of the spinneret holes is 3-5:1.
Specifically, the annular groove 3 is provided with a rubber ring for sealing the joint of the first plate body 1 and the raw liquid feeding pipeline to prevent liquid leakage.
Specifically, the annular groove 5 is provided with a rubber ring for sealing the joint of the first plate body 1 and the second plate body 2 to prevent liquid leakage.
The top of the first plate body 1 of the spinneret plate is propped against a stock solution feeding pipeline, the spinning stock solution flows into the through hole 4 through the feeding pipeline, passes through the first plate body 1, flows into the slurry inlet channel 6, flows into the annular containing cavity 7, is extruded through the second plate body 2, and is obtained, the spinning stock solution with a hollow section is solidified and formed, and is drawn to form a primary fiber with the hollow section, as shown in fig. 2, and then the hollow section carbon fiber is obtained through a subsequent process.
Example 1
96Wt% of acrylonitrile is used as a first monomer, 5wt% of methyl acrylate is used as a second monomer, free radical solution polymerization is carried out in dimethyl sulfoxide, so as to obtain spinning solution, the temperature of the spinning solution is controlled to be 60 ℃, and the solid content is controlled to be 20%. The spinning solution is subjected to single removal under the pressure of-76 Kpa in a single removal kettle, is subjected to primary filtration treatment of 3 mu m, is subjected to defoaming treatment in a defoaming kettle with the pressure of-97 KPa, is sent to secondary filtration of 1 mu m for treatment, and is pressurized and conveyed to a spinning unit after refining treatment. The spinning dope was extruded through a1 μm wick filter, pressurized and then through a spinneret having an annular cavity at an extrusion speed of 15.49m/min. The spinneret plate material with the annular containing cavity is 316L alloy, the needle cylinder of the first plate body is 3K, the needle diameter is 0.5mm, the number of the microporous through holes of the second plate body is 3K, the micropore diameter is 1.0mm, and the length-diameter ratio of the spinneret plate holes is 3:1. The spinning solution enters a coagulating bath for coagulating and forming after passing through an air layer of 1mm, the concentration of the coagulating bath is 45wt%, the temperature of the coagulating bath is 5 ℃, and meanwhile, a draft multiple of 1.05 times is applied to obtain nascent fibers. The nascent fiber is subjected to multistage desalted water at 35 ℃ to remove the solvent, washed with water, and then subjected to hot water at 70 ℃ and simultaneously subjected to 1.3 times drafting. The fiber after hot water drawing was passed through an oil bath having a concentration of 1.10%. And drying and densification treatment is carried out on the fibers subjected to oiling through a hot roller with temperature gradient change of 100-185 ℃, and the pressure of the drying roller is kept to be 0.55MPa, and the number of the drying rollers is 25. And (3) carrying out steam drafting on the dried and densified fiber bundles, wherein the saturated steam pressure is 0.45MPa, and the steam drafting multiple is 3.55 times. And (5) winding and forming after steam drafting to obtain the hollow section precursor. The precursor is pre-oxidized in a pre-oxidizing furnace after passing through a filament withdrawing frame, the pre-oxidizing temperature is 240 ℃, and the pre-oxidizing draft multiple is 0.98 times. The pre-oxidized fiber is carbonized sequentially through a low-temperature furnace and a high-temperature furnace to prepare the carbon fiber with the hollow section, the temperature of the low-temperature furnace is controlled to be 600 ℃, the draft multiple of the low-temperature furnace is controlled to be 1.02 times, the temperature of the high-temperature furnace is controlled to be 1500 ℃, and the draft multiple of the high-temperature furnace is controlled to be 1.01 times. The core-sheath ratio of the prepared carbon filament is 3%, the internal-external diameter ratio E i is 58%, and the relative deviation is 16%.
Example 2
96Wt% of acrylonitrile is used as a first monomer, 4wt% of acrylic acid is used as a second monomer, free radical solution polymerization is carried out in dimethyl sulfoxide, so as to obtain spinning solution, the temperature of the spinning solution is controlled to be 60 ℃, and the solid content is controlled to be 20%. The spinning solution is subjected to single removal under the pressure of-76 Kpa in a single removal kettle, is subjected to primary filtration treatment of 3 mu m, is subjected to defoaming treatment in a defoaming kettle with the pressure of-97 KPa, is sent to secondary filtration of 1 mu m for treatment, and is pressurized and conveyed to a spinning unit after refining treatment. The spinning dope was extruded through a1 μm wick filter, pressurized and then through a spinneret having an annular cavity at an extrusion speed of 15.49m/min. The spinneret plate material with the annular containing cavity is 316L alloy, the needle cylinder of the first plate body is 3K, the needle diameter is 0.6mm, the number of the microporous through holes of the second plate body is 3K, the micropore diameter is 1.2mm, and the length-diameter ratio of the spinneret plate holes is 4:1. The spinning solution enters a coagulating bath for coagulating and forming after passing through an air layer of 1mm, the concentration of the coagulating bath is 45wt%, the temperature of the coagulating bath is 5 ℃, and meanwhile, a draft multiple of 1.05 times is applied to obtain nascent fibers. The nascent fiber is subjected to multistage desalted water at 35 ℃ to remove the solvent, washed with water, and then subjected to hot water at 70 ℃ and simultaneously subjected to 1.3 times drafting. The fiber after hot water drawing was passed through an oil bath having a concentration of 1.10%. And drying and densification treatment is carried out on the fibers subjected to oiling through a hot roller with temperature gradient change of 100-185 ℃, and the pressure of the drying roller is kept to be 0.55MPa, and the number of the drying rollers is 25. And (3) carrying out steam drafting on the dried and densified fiber bundles, wherein the saturated steam pressure is 0.45MPa, and the steam drafting multiple is 3.55 times. And (5) winding and forming after steam drafting to obtain the hollow section precursor. The precursor is pre-oxidized in a pre-oxidizing furnace after passing through a filament withdrawing frame, the pre-oxidizing temperature is 240 ℃, and the pre-oxidizing draft multiple is 0.98 times. The pre-oxidized fiber is carbonized sequentially through a low-temperature furnace and a high-temperature furnace to prepare the carbon fiber with the hollow section, the temperature of the low-temperature furnace is controlled to be 600 ℃, the draft multiple of the low-temperature furnace is controlled to be 1.02 times, the temperature of the high-temperature furnace is controlled to be 1500 ℃, and the draft multiple of the high-temperature furnace is controlled to be 1.01 times. The prepared carbon fiber has a sheath-core ratio of 0%, an internal-external diameter ratio E i of 55% and a relative deviation of 10%.
Example 3
And (3) taking 95wt% of acrylonitrile as a first monomer, 5wt% of isobutyl methacrylate as a second monomer, and performing free radical solution polymerization in dimethyl sulfoxide to obtain a spinning solution, wherein the temperature of the spinning solution is controlled to be 60 ℃ and the solid content is controlled to be 20%. The spinning solution is subjected to single removal under the pressure of-76 Kpa in a single removal kettle, is subjected to primary filtration treatment of 3 mu m, is subjected to defoaming treatment in a defoaming kettle with the pressure of-97 KPa, is sent to secondary filtration of 1 mu m for treatment, and is pressurized and conveyed to a spinning unit after refining treatment. The spinning dope was extruded through a 1 μm wick filter, pressurized and then through a spinneret having an annular cavity at an extrusion speed of 15.49m/min. The spinneret plate material with the annular containing cavity is 316L alloy, the needle cylinder of the first plate body is 3K, the needle diameter is 0.5mm, the number of the microporous through holes of the second plate body is 3K, the micropore diameter is 1.5mm, and the length-diameter ratio of the spinneret plate holes is 3:1. The spinning solution enters a coagulating bath for coagulating and forming after passing through an air layer of 1mm, the concentration of the coagulating bath is 45wt%, the temperature of the coagulating bath is 5 ℃, and meanwhile, a draft multiple of 1.05 times is applied to obtain nascent fibers. The nascent fiber is subjected to multistage desalted water at 35 ℃ to remove the solvent, washed with water, and then subjected to hot water at 70 ℃ and simultaneously subjected to 1.3 times drafting. The fiber after hot water drawing was passed through an oil bath having a concentration of 1.10%. And drying and densification treatment is carried out on the fibers subjected to oiling through a hot roller with temperature gradient change of 100-185 ℃, and the pressure of the drying roller is kept to be 0.55MPa, and the number of the drying rollers is 25. And (3) carrying out steam drafting on the dried and densified fiber bundles, wherein the saturated steam pressure is 0.45MPa, and the steam drafting multiple is 3.55 times. And (5) winding and forming after steam drafting to obtain the hollow section precursor. The precursor is pre-oxidized in a pre-oxidizing furnace after passing through a filament withdrawing frame, the pre-oxidizing temperature is 240 ℃, and the pre-oxidizing draft multiple is 0.98 times. The pre-oxidized fiber is carbonized sequentially through a low-temperature furnace and a high-temperature furnace to prepare the carbon fiber with the hollow section, the temperature of the low-temperature furnace is controlled to be 650 ℃, the draft multiple of the low-temperature furnace is controlled to be 1.02 times, the temperature of the high-temperature furnace is controlled to be 1600 ℃, and the draft multiple of the high-temperature furnace is controlled to be 1.01 times. The prepared carbon fiber has a sheath-core ratio of 0%, an internal-external diameter ratio E i of 40% and a relative deviation of 17.6%.
Example 4
This example is substantially the same as example 3, except that the filaments are pre-oxidized in a pre-oxidation furnace through a draw back frame at a pre-oxidation temperature of 220 ℃ and a pre-oxidation draft of 0.98 times. The pre-oxidized fiber is carbonized sequentially through a low-temperature furnace and a high-temperature furnace to prepare the carbon fiber with the hollow section, the temperature of the low-temperature furnace is controlled to be 580 ℃, the draft multiple of the low-temperature furnace is controlled to be 1.02 times, the temperature of the high-temperature furnace is controlled to be 1450 ℃, and the draft multiple of the high-temperature furnace is controlled to be 1.01 times. The prepared carbon fiber has a sheath-core ratio of 0%, an internal-external diameter ratio E i of 40% and a relative deviation of 8%.
Comparative example 1
This comparative example is substantially the same as example 3, except that the coagulation bath concentration is 55wt% and the coagulation bath temperature is 23 ℃. The prepared precursor has a flat structure, the internal-external diameter ratio E i is 58%, and the relative deviation is 67%.
Comparative example 2
This comparative example is substantially the same as example 3 except that the needle diameter in the needle-containing cylinder is 0.8mm, the pore diameter of the micropores in the micropore-containing through holes is 1.2mm, and the aspect ratio of the spinneret holes is 5:1. The prepared precursor has a flat structure, the internal-external diameter ratio E i is 53%, and the relative deviation is 20.9%.
Comparative example 3
This comparative example is substantially the same as example 3 except that the needle diameter in the needle-containing cylinder is 0.3mm, the pore diameter in the micropore-containing through-hole is 0.5mm, and the aspect ratio of the spinneret orifice is 4:1. The prepared precursor has a flat structure, the internal-external diameter ratio E i is 34%, and the relative deviation is 43.3%.
Comparative example 4
This comparative example is substantially the same as example 3 except that the needle diameter in the needle-containing cylinder is 0.3mm, the pore diameter of the micropores in the micropore-containing through holes is 1.5mm, and the aspect ratio of the spinneret holes is 3:1. The prepared carbon wire is of a solid structure, and the sheath core rate is 11.6%.
Comparative example 5
This comparative example is substantially the same as example 3 except that the pre-oxidized fiber is carbonized sequentially by a low temperature furnace and a high temperature furnace to prepare a carbon fiber having a hollow cross section, the temperature of the low temperature furnace is controlled to 650 ℃, the draft multiple of the low temperature furnace is 1.02 times, the temperature of the high temperature furnace is controlled to 1650 ℃, and the draft multiple of the high temperature furnace is 1.01 times. The core-sheath ratio of the prepared carbon filament is 2%, the internal-external diameter ratio E i is 40%, and the relative deviation is 43%.

Claims (10)

1. The preparation method of the polyacrylonitrile dry-jet wet-spinning carbon fiber with the hollow section is characterized by comprising the following steps of:
(1) Taking 95-99 wt.% of acrylonitrile as a first monomer, and taking 1-5 wt.% of acrylic acid, methyl acrylate, methyl methacrylate or isobutyl methacrylate as a second monomer, and performing solution polymerization in dimethyl sulfoxide to obtain a spinning solution, wherein the temperature of the spinning solution is controlled to be 40-70 ℃ and the solid content is controlled to be 10-25%;
(2) Extruding spinning stock solution through a spinneret plate with an annular containing cavity under pressure after removing and defoaming, wherein the extruding speed is 10-20 m/min, then entering a dimethyl sulfoxide coagulating bath through an air layer for coagulating phase separation to form gel fine strips, simultaneously carrying out drafting to obtain nascent fibers with hollow sections, wherein the coagulating bath concentration is 30-50 wt%, the coagulating bath temperature is 5-20 ℃, the spinneret plate with the annular containing cavity comprises a first plate body (1) and a second plate body (2), a plurality of through holes (4) and a plurality of needle-containing cylinders (8) are arranged on the first plate body (1), annular grooves (3) are arranged at the top, annular grooves (5) are arranged at the bottom, a plurality of micro-hole-containing through holes (9) are arranged on the second plate body (2), a pulp inlet channel (6) is formed by attaching the first plate body (1) and the second plate body (2), the needle-containing cylinders (8) on the first plate body and the micro-hole-containing through holes (9) on the second plate body are in one-to-one correspondence, the first plate body (1) and the second plate body (2) are connected with the pulp inlet channel (6), the pulp inlet channel (6) is connected with the top of the first plate body (1) and the top of the first plate body (2) and the first plate body (1) and the top of the second plate body (2) and the top of the pulp inlet channel (6) has the same length as the needle-containing cavity (1), the diameter of the needle-containing cylinder (8) is 0.5-0.6 mm, the aperture of the micropore in the micropore-containing through hole (9) is 1.0-1.5 mm, and the length-diameter ratio of the spinneret orifice is 3-4:1;
(3) The primary fiber is subjected to multistage desalination water washing to remove solvent, water washing, hot desalted water washing and drafting;
(4) Oiling the fiber after hot water drafting, and drying and densification by a hot roller;
(5) The fiber after drying and densification enters into steam drafting, and is coiled and formed after the steam drafting, so as to obtain a hollow section precursor;
(6) The hollow section precursor enters a pre-oxidation furnace for pre-oxidation through a filament withdrawing frame to obtain pre-oxidized filaments;
(7) The pre-oxidized fiber is carbonized through a low-temperature furnace and a high-temperature furnace in sequence to prepare the carbon fiber with the hollow section, wherein the temperature of the low-temperature furnace is 580-650 ℃, the draft multiple of the low-temperature furnace is 1.0-1.1 times, the temperature of the high-temperature furnace is 1450-1600 ℃, and the draft multiple of the high-temperature furnace is 0.95-1.05 times.
2. The preparation method of the spinning dope according to claim 1, wherein in the step (2), the spinning dope is subjected to the process of removing the sheets under the pressure of-76 Kpa in a removing kettle, subjected to the process of primary filtration of 3 μm, subjected to the process of deaeration in a deaerating kettle with the pressure of-97 Kpa, and then subjected to the process of secondary filtration of 1 μm.
3. The method according to claim 1, wherein in the step (2), the air layer is 1 to 5mm in height and the air draft is 1 to 2 times.
4. The method according to claim 1, wherein in the step (2), the coagulation bath concentration is 45 wt% and the coagulation bath temperature is 5 ℃.
5. The preparation method of the porous ceramic material according to claim 1, wherein in the step (2), the number of holes of the through holes (4) is 1-2K, the number of holes of the needle-containing cylinder (8) and the number of holes of the micropore-containing through holes (9) are the same, the number of the needle-containing cylinder (8) and the number of micropores of the micropore-containing through holes (9) are both 1-5K, the needle length of the needle-containing cylinder (8) and the micropore length of the micropore-containing through holes (9) are both 0.3-1.0 mm, the length of the cylinder of the needle-containing cylinder (8) is 10-15 mm, the diameter of the cylinder is 3-5 mm, the length of the through holes of the micropore-containing through holes (9) is 5-8 mm, the diameter of the through holes is 4-6 mm, the hole spacing is 1-3 mm, and the spinneret plate with an annular containing cavity is made of hastelloy C276, 316L alloy, 1Cr18Ni9Ti austenitic stainless steel, AISI316 or AISI630.
6. The preparation method according to claim 1, wherein in the step (3), the washing tank is 3-7 stages, the washing temperature is 20-36 ℃, the draft ratio is 1-1.5 times, the hot desalted water washing and the draft are 1-3 stages, the temperature is 60-80 ℃, and the draft ratio is 1-2.0 times.
7. The method according to claim 1, wherein in the step (4), the temperature of the hot roller is 3-7, the temperature range is 100-185 ℃, and the pressure of the hot roller is 0.30-1.10 mpa.
8. The method according to claim 1, wherein in the step (5), the steam pressure is 0.30 to 0.80mpa, the steam draft ratio is 3.0 to 5.0 times, and the winding speed is 350 to 500m/min.
9. The method according to claim 1, wherein in the step (6), the pre-oxidation temperature is 200 ℃ to 300 ℃ and the pre-oxidation draft is 0.9 to 1.05 times.
10. The method according to claim 9, wherein the pre-oxidation temperature is 220 ℃ to 240 ℃.
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